As the use of digital data increases, the demand for faster, smaller, and more efficient memory structures increases. One type of memory structure that has recently been developed is a crossbar memory structure. A crossbar memory structure includes a set of upper parallel wires that intersect a set of lower parallel wires. A programmable memory element configured to store digital data is pieced at each intersection of the wires.
One type of programmable memory element that may be used is a memristive element. A memristive dement is a device that changes the state of its resistance based on an applied programming condition. For example, a programming condition may be applied to change the memristive element from a high resistive state to a low resistive state or vice versa. A high resistive state may represent a digital “1” and a low resistive state may represent a digital “0”.
One challenge that results from use of a crossbar memory structure is the process of reading the state of a target memory element within the crossbar array. The state of a memory element may be determined by applying a sense voltage to the target memory element. Then, the electric current flowing through the target memory element will be indicative of the resistive state of the target memory element. However, when applying a sense voltage to a target memory element, the electric current flowing from the target memory element will be adversely affected by the half-selected memory elements within the crossbar array. It is difficult, therefore, to isolate the electric current flowing through the target memory element that is resulting from only the applied sense voltage across the target memory element.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.